Printing plate and process of preparing same



Oct. 9, 1934. w. SAUNDERS 1,975,867

lV/LL/AM 5A l/NOERS NNNNNN O R w gm AT ORNEY I Patented Oct. 9, 1934PRINTING PLATE AND PaooEss or TPREPIARINGQ SAME -Williani Saunders,-Baldwin, N. Y.

Application September'19,1933, sari-amending) r} 1 Claim. (01. 101-40131 such service, there is a tendency of the makeready to slip and to getout of register in the operation of the press.

It is the purpose of the present invention to overcome and eliminate thefeatures mentioned and in a sense to incorporate the make-ready in theplate itself.

These objects and others of desirable nature are attained by the novelfeatures of invention in process and structure as hereinafter definedand broadly claimed.

The drawing accompanying and forming part of the specificationillustrates the mode of procedure and the strcture embodying theinvention and as the same is by way of disclosure rather thanlimitation, it is to be understood that the process and structure may bemodified and changed from such illustration all within the true intentand broad scope of the invention.

Fig. 1 is a face view of an electrotype plate.

Fig. 2 is a cross-sectional View of the same as on line 2--2 of Fig. 1.

Fig. 3 is a face view of the make-ready taken from this plate.

Fig. 4 is a cross-sectional view of this makeready as on line 4i of Fig.3.

Fig. 5 is a broken cross-sectional View showing the make-ready reversedand applied to the back of the plate in registered relation with thesubject on the face of the plate.

Fig. 6 is a broken sectional detail illustrating the operation ofimpressing the make-ready into the plate in a hydraulic press or thelike.

Fig. 7 is a broken sectional detail illustrating the plate with themake-ready raised on the face of the same.

Fig, 8 is a similar detail showing the back of the plate shaved to bringthe plate to normal thickness and trimmed ready for use in a printingpress.

The electrotype shown in Figs. 1 and 2 may be considered as illustrativeof printing plates generally to which the invention is applicable,having the high and low printing and non-printing portions 9 and 10respectively.

The make-ready shown in Figs. 3 and 4'- also may be considered astypical and produced by known methods from overlay paper or the like andembodying the backing or foundation sheet 11 and the raised overlaysurfaces 12.

The invention departs from the usual practice 0. in that instead ofusing the overlay in cooperation with the face of the plate, it isregistered and impressed into the back of the plate to raise theprinting surfaces on the face of the plate.

As a first step of this new process, the makeready is reversed andregistered on the back of the plate as in Fig. 5, with raised portions12 of the overlay in register with corresponding printing surfaces 9 onthe front of the plate. The make-ready is suitably secured in thisregistered v relation on the back of the plate, as with a suitable pasteor cement and pressure is applied while so registered, to bring up themake-ready on the face of the plate.

The latter operation is illustrated in Fig. 6, where 13 and 14 indicatethe companion elements of a hydraulic or other suitable press. Ayielding bed for the face of the plate 15 is here shown provided by alayer 16 of lead or like material, which may have a backing 1'7, ofnewsprint paper or other suitable cushioning medium.

The pressure required varies with the character of the plate. Foraverage purposes, 12,000 lbs. to the square inch may be sufficient. Theeffect of such pressure is apparent in Figs. 6 and '7, which show howthe raised overlay portions on the back cause corresponding areas to bedisplaced and hence the surfaces of similar outline to be raised orlifted on the face of the plate as indicated at 9'. These raised areas,conforming to the overlay thus have the effect of a makereadyincorporated directly in the plate. Hence, no external make-ready isnecessary with these new process plates.

The processing described has the effect of increasing the overallthickness of the plate and usually after this raising operation, theback of the plate is shaved as at 18, in Fig. 8, to restore it tooriginal or intended thickness, ready for use on the printing press.This shaving operation may be part of the same process by which theplate is trimmed about the edges, at 19.

By impressing the make-ready into the back of the plate, the printingsurfaces are raised in direct correspondence with their values as provedup on the make-ready. Consequently, the plate thus processed givesaccurate values in the matters of depth and detail and the make-readybeing in effect a permanent part of the plate itself, {19

can not get out of register or lose its effect from the pounding of thepress. The invention is applicable to curved as well as to flat platesand is of particular value for fine work, where with prior processesintermediate values have been lost, due to inaccuracies in themake-ready and the like. The paper overlay prevents distortion orshearing of the plate and brings up the intermediate tone values, whichare of special importance in fine half tone work.

What is claimed is:

The herein disclosed method of incorporating the make-ready in anelectrotype or similar printing plate and which comprises taking a prooffrom the printing face of the plate on overlay paper, reversing saidproof and registering the same in reversed relation on the back of theplate with the corresponding printing areas on the face of the plate,temporarily securing the plate in correspondence with the registeredoverlay proof on the back of the plate, said raised portions sinking toa corresponding extent into the lead-like face covering layer ofmaterial, stripping the overlay proof paper from the back of the raisedplate and then shaving the impressed back of the raised plate to restoreit to the original or intended thickness for use on a printing press.

WILLIAM SAUNDERS.

